Reproduction of sound



Nov. 2, 1937.

a. 1.. DlMMlCK REPRODUCTION OF SOUND Filed Jan. 19; 1955 ATTORNEYPatented Nov. 2, 1937 PATENT OFFICE REPRODUCTION OF SOUND Glenn L.Dimmick, Haddonfield, N. J., assignor to Radio Corporation of America, acorporation of Delaware Application January 19, 1935, Serial No. 2,460

5 Claims.

This invention relates to the photographic recording and reproducing ofsound, and has for its principal object the provision of an improvedapparatus and method of operation whereby types of sound recordsheretofore capable of being reproduced only in different types ofdevices may be reproduced by the same device.

In my copending application Serial No. 610,302 filed May 9, 1932, isdisclosed a sound record on which the positive and negative undulationsare recorded on separate tracks spaced from one another so as to permittheir images to be focused separately on difierent light responsiveelements. As pointed out in the aforesaid application, this spacing ofthe component parts of the record has the advantage that fogging betweenpeaks at high frequency is avoided, background noise is eliminated, thetendency of an alternating current exciter lamp to produce hum in thereproduced sound is neutralized and the development of the film issimplified.

A further object of this invention is to provide an apparatus operableto reproduce sound records irrespective of whether the positive andnegative undulations are recorded together or separately on tracksspaced apart from one another. In accordance with the invention, thelight beam modulated by the sound-record is split into differentcomponents and these components are applied to the same or to differentlight sensitive elements depending on whether the negative and positivesound impulses are recorded on the same or difierent tracks or areas.

The invention will be better understood from the following descriptionwhen considered in connection with the accompanying drawing, and itsscope will be pointed out by the appended claims.

The singlefigure of the drawing is a diagrammatic illustration of asound reproducing apparatus embodying the invention.

This apparatus includes an exciter lamp Ii] from which light or"substantially constant intensity is applied to the sound record of afilm ll through an optical system I2. The sound recrd of the film Il maybe either the push-pull type of record disclosed by the aforesaidapplication or a record having all the sound components recorded on asingle track. In either case the light beam acoustically modulated bythe record of film or strip II is transmitted through lenses and issplit by lenses l4 and I5 into two separate beams one of which isapplied toa stationary reflector l6 and the other of which is applied toan adjustable reflector ll.

With the reflectors l6 and I! in their full-line 5 illustrated positionsone of the acoustically modulated light beams is reflected by thestationary reflector Hi to the cathode I 8 of a light sensitive deviceand the other light beam is reflected by the adjustable reflector I! tothe cathode 2! of 10 the device [9. From the device l9, acousticallymodulated current is supplied to a utilization apparatus such as a loudspeaker, through means including an electrical source 22 connected tothe lead of anode 23, a transformer 24, suitable amplifiers (not shown)etc. Under these conditions, a record having its negative and positiveimpulses separately recorded on tracks spaced from one another isreproduced with all the advantages pointed out above.

When a record having all the sound components recorded on a single trackis to be reproduced, the mirror His shifted to the dotted line positionand the two light beams are reflected to the cathode I8 and convertedinto corresponding electrical impulses in a manner too well understoodto require further description. It will be apparent that any suitabletype of electrical connection other than that illustrated may beutilized and that additional component lightbeams may be controlled inthe manner herein described.

I claim:

1. The combination of means for producing a plurality of acousticallymodulated light beams, a light sensitive device provided with aplurality of cathodes, means for directing selected portions of saidbeam, separate cathodes and means for selectively directing saidportions to a single cathode.

2. The combination of means for producing a plurality of acousticallymodulated light beams, a light sensitive device provided with aplurality of cathodes, and means including a stationary reflectorinterposed in the path of one of said beams for directing said beam toone of said cathodes and an adjustable reflector interposed in the pathof another of said 'beams for directing said beam to the same cathode orto a different cathode of said device.

5. In combination, means for directing a beam of light through a filmsound track, means for dividing said beam into two portions, and meansfor alternatively directing said portions either onto two cathodes of alight sensitive device connected in a push pull circuit or onto only onecathode thereof, whereby either a push pull sound track or an ordinarysound track may be reproduced for the same apparatus.

GLENN L. DIMNHCK.

- CERTIFICATE OF CORRECTION.

Patent No. 2,097,758. November 2, 1957,

GLENN L. DIMMICK.

It is hereby eertified that error appears in the printed specificationof the above numbered patent requiring correction as follows; Page 1,second column, line 58, after "beam strike out the comma and insertinstead the word "to; and that the said Letters Patent should be readwith this correotion therein that the same may conform to the recordofthe case in the Patent Office. a i

Signed and sealed this 1st day of February, A. D. 1958.

Henry Van'Arsdale, Acting Commissioner of Patents.

